1. The Field of the Invention
The present invention relates generally to sheet handling systems of sheet fed presses, and, more particularly, to a non-contact sheet handling system for use at the delivery of a sheet fed press.
2. Description of Related Art
In sheet fed presses, after each sheet passes through the last printing unit of the press, the sheet enters an area of the press known as "the press delivery". The press delivery includes, among other thing, devices for drying or setting the ink on the printed sheets. Such devices include, for example, air showers and infra red (IR) drying heads, or ultra violet (UV) drying heads.
Printed sheets move through typical sheet fed press deliveries by sliding across a series of parallel rods. The sheets are carried across the top of a plurality of rods (typically five), which run parallel to the direction of sheet movement. A series of gripper bars, which move along a track, carry the sheets through the delivery. Specifically, each gripper bar is propelled along a motorized track that also runs parallel to the movement of the sheet through the delivery. Each gripper bar has a series of metal fingers that grasp the leading edge of a printed sheet allowing it to drag the sheet over the rods, through the delivery. Because the printed sheets slide across and are in physical contact with the rods, such systems are referred to as "contact" sheet handling systems.
Contact sheet handling systems place limitations on the usable area of each sheet. Specifically, the sheets cannot have printed material in the areas where the sheet contacts any of the rods. If a printed area of a sheet were to contact the rods, the ink would smear. Accordingly, the printable area of the sheet is limited by the contact sheet handling systems. Therefore, a need exists for an improved sheet handling system, particularly one that provides a greater usable area per sheet.
3. Summary of the Invention
The present invention satisfies such a need. A non- contact sheet handling system according to one embodiment of the present invention includes a manifold and an air pan. The system also includes a first valve controlling air flow to the manifold and a second valve for controlling air flow from the manifold to the air pan. A non-contact plate having openings covers the air pan. In various alternate embodiments, the system further includes a diffuser that diffuses air flow through the interior of the air pan.
Similarly, a method according to an embodiment of the present invention includes adjusting a first and a second valve to control the level of air flow to a first and second region of the system. The method further includes adjusting a third valve to get the air flow to the first and second valves. In an alternate embodiment, the air flow is also diffused before being directed to at least the first areas.